[1] Johnston was originally created for printing (with a planned height of 1 inch or 2.5 cm), but it rapidly became used for the enamel station signs of the Underground system as well.

Johnston greatly admired Roman capitals, writing that they "held the supreme place among letters for readableness and beauty.

[6] Johnston's alphabet marked a break with the kinds of sans serif then popular, now normally known as grotesques, which tended to have squarer shapes inspired by signwriting and Didone type of the period.

[8] The lower case i and j have diagonally-placed square dots or tittles, a motif that in some digitisations is repeated in the full stop, commas, apostrophes and other punctuation marks.

"[16] Pick specified to Johnston that he wanted a typeface that would ensure that the Underground Group's posters would not be mistaken for advertisements; it should have "the bold simplicity of the authentic lettering of the finest periods" and belong "unmistakably to the twentieth century".

As early as 1937, the LPTB mentioned it as a package promoting the system's billboards to advertisers as an example of its commitment to stylish design, along with its commission of art from Feliks Topolski.

Johnston's original design came with two weights, ordinary and bold, while condensed letters soon followed for use on buses to show routes and destinations.

London Transport often did not use Johnston for general small printing, with many documents such as bus timetables using other typefaces such as Gill Sans and Granby.

After all precisely hand-drawn letters (nearly 1,000) were completed and sent to AlphaType for digitisation in the US in 1981–82, New Johnston finally became ready for Linotron photo-typesetting machine, and first appeared in London's Underground stations in 1983.

Punctuation marks are matched the diamond tittle, differing from Johnston's original design, enhancing the identity of London Transport.

In 1990–1992 Banks and Miles, in partnership with Signus Limited digitised the first PostScript Type 1 fonts for the then London Transport under the auspices of the corporate design manager, Roger Hughes.

Hughes and Jeremy Rewse-Davies, LT's design director, also commissioned New Johnston Book, a special weight with distinctive modifications to allow better representation on low-resolution laser printers.

The New Johnston Book weight was designed specifically for high volume publications and its usage was intended to be restricted to sizes below 12pt.

In early 2007, a digitisation of the typeface was developed by Transport for London under the name Johnston Delf Smith for its own use on historic signs.

Separate small caps (romans only) and old style figure faces were also released for each weight in TrueType and PostScript formats, for a total of fifteen typefaces.

Railway Sans is an open-source interpretation of Johnston's original (regular weight) by Justin Howes and Greg Fleming.

[34] It includes a number of alternate glyphs such as a Garamond-inspired W (used on old signs at West Brompton station), ligatures and a characteristic arrow design.

[35] Paddington is a basic public domain digitisation by Stephen Moye, including italic, bold, and small caps designs.

[36][37] Its use has included the Tube map (sometimes hand-lettered), nameplates and general station signing, as well as much of the printed material issued by the Underground Group and its successors; also by the nationalised British Road Services in the immediate post-war era.